FUNCTIONS OF THE BRAIN. 91 



exactly as the organic parts are diminished in number and 

 simplified, the vital phenomena become fewer and more 

 simple; and each function ends, when the respective organ 

 ceases. This is true throughout zoology ; there is no ex- 

 ception in behalf of any vital manifestations. 



The same kind of facts, the same reasoning, the same sort 

 of evidence altogether, which shew digestion to be the 

 function of the alimentary canal, the motion of the muscles, 

 and various secretions of their respective glands, prove 

 that sensation, perception, memory, judgment, reasoning, 

 thought — in a word, all the manifestations called mental or 

 intellectual — are the animal functions of their appropriate 

 organic apparatus, the central organ of the nervous system. 

 No difficulty nor obscurity belongs to the latter case, which 

 does not equally affect all the former instances : no kind of 

 evidence connects the living processes with tlie material in- 

 struments in the one, which does not apply just as clearly 

 and forcibly to the other. 



Shall I be told that thought is inconsistent with matter ; 

 that We cannot conceive how medullary substance can per- 

 ceive, remember, judge, reason? 1 acknowledge that we 

 are entirely ignorant how the parts of the brain accomplish 

 these purposes — as we are how the liver secretes bile, how 

 the muscles contract, or how any other living purpose is ef- 

 fected ', — as we are how heavy bodies are attracted to tlie 

 earth, how iron is drawn to the magnet, or how two salts de- 

 compose each other. Experience is, in all these cases, our 

 sole, if not sufficient instructress ; and the constant con- 

 j unction of phenomena, as exhibited in her lessons, is the 

 sole ground for affirming a necessary connexion between 

 them. If we go beyond this, and come to inquire the man- 

 ner how, the mechanism by which these things are effi^cted, 

 we shall find every thing around us equally mysterious, 

 equally incomprehensible — from the stone which falls to 

 the earth, to the comet traversing the heavens — from the 

 thread attracted by amber or sealing-wax, to the revolutions 

 of planets in their orbits — from the formation of a maggot 



